Breathing assistance systems are generally operable to provide breathing assistance to a patient. Examples of breathing assistance systems include ventilators, continuous positive airway pressure (CPAP) systems, and bi-level positive airway pressure (BiPAP) systems. In certain breathing assistance systems, one or more self contained power supplies (e.g., one or more batteries) may supply power to the systems. Such self contained power supplies may reduce or eliminate the need for a nearby electrical outlet to supply power.